Special-service telephone system.



v T. e. MARTIN. SPECIAL SERVICE TELEPHONI SYSTEM.

IVPLICAVTION FILED IA-YII- I912- 1,1 59,855. Patented Nov. 9, 1915.

- 3 HEE'ISSHEETI. I II L2 7 5% {I VL/JTNESSES MENTOR:

T. G. MARTIN.

SPECIAL SERVICE TELEPHONE SYSTEM.

APPLICATION FILED nun. Hill.

1, 1 59,855. Patented Nov. 9, 1915.

3 SHEETSSHEET 2.

W/T/VE5555 mum/70K.-

TTOR/YEYS.

T. G. MARTIN.

SPECIAL SERVICE TELEPHONE SYSTEM.

. APPLICATION FILED IAYH, 19l2.

1,159,855. Patented Nov. 9, 1915.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

TALBOT G. MARTIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SPECIAL-SERVICE TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Nov. 9, 1915.

To all whom it may concern:

Be it known that I, TALBOT G. MARTIN, a citizen of the United States ofAmerica, and resident of Chicago, in the county ofCook and State ofIllinois, have invented certain new and useful Improvements in SpecialService Telephone Systems, ofwhich the following is a specification.

Hy invention relates to special service telephone systems, and comprisesan ar-. rangement of circuits whereby the subscribers of a telephonesystem, either manual or automatic, may be automatically supplied withmusic, news or information of any kind from a central distributingsource. In order to accomplish this result I provide a loud speakingtelephone receiver which may be bridged across the subscribers line, andat the central station I provide a special transmitting circuit which isbridged across the line, and thus the subscriber, by merely operating akey, or throwing a switch in some other manner, can connect his loudspeaking receiver directly with this special transmitting circuit. Ilikewise provide means whereby, when a subscriber wishes to establishconnection with some other subscriber, this special transmitting circuitis automatically disconnected from the line, so that it does not in anyway interfere with the establishment of such connection.

My invention is adapted for and associated with either an automatic or amanual line. In connection with the automatic system I provide meanswhereby the special service circuit is automatically disconnected assoon as a subscriber removes his receiver from the hook preparatory tomaking a call. I also provide means whereby the circuit is disconnectedwhen a connector switch connects with a line. In connection with themanual system, however, this special service circuit is automaticallydisconnected by the operator plugging into the jack of the line, whetherthis line he a calling or a called line.

These and other objects of my invention will be more readily understoodby reference to the accompanying drawings, in which similar referencecharacters refer to similar parts.

Figures 1, 2 and 3 show a complete connection between a callingsubstation A (Fig, 1) and a called substation A (Fig. 3) in a systemembodying the principles of my innormally vention. In Fig. 1 there isrepresented an automatic substation A to the line conductors of whichthere is allotted at the central oiiice an individual or line switch C.Q At D there is shown a master switch for controlling a group of lineswitches C. All the line switches of this group have-common access to anumber of trunk lines which lead to first selector switches, one ofwhich is represented at E in Fig. 2. A number of first selectors havecommon access to a plurality of second selectors, one of which isrepresented at F. The second selectors in turn have ac cess. toconnector switches, one of which is shown at H in Fig. '3, by means ofwhich connections may be completed with the subscribers lines. Figs. 4and 5 represent diagrammatical modifications of the circuits, which willbe fully described hereinafter. Fig. 6 is a diagram showing how myinvention may be applied to a manual telephone system.

The automatic substations A and A may be of any suitable orapprovedtype. Those with which I have chosen to illustrate my invention, and asillustrated at A in Fig. 1, comprise the usual receiver 25, switch hook26, transmitter 27, ringer 29 and condenser 30. In addition, thesubstation Ais provided with the impulse springs 31 and 32 and animpulse wheel 33. The impulse wheel 33 carries upon its periphery theimpulse teeth 34 and is secured to a shaft 35, to which latter there isalso attached a dial (not shown) provided with finger holes, through themedium of which holes the impulse wheel may be rotated. As the impulsewheel is returned to normal position by a spring (not shown) after ithas been rotated' for any digit,each of the teeth 34 which passes theend of jthe spring 31 forces said spring out of engagement with thespring 32. The number of times these springs are separated depends uponthe digit called. The substation A is also provided with a loud speakingreceiver 2 which maybe of any suitable type. This receiver is normallydisconnected from the line, but may be bridged across the lineconductors 98 and 99 through vthe condensers 3 and 4: by means of themanually-operated key K.

The line switch C, which is individual to the line of substation A, andthe master switch D are modified forms of the general typeof line switchand master switch disclosed in British patent to R. W. James No. 26,301of 1906, the master switch D, however, being of the particular typeshown in British patent to T. G. Martin No. 1419 of 1910. The lineswitch. C is a slightly modified construction of the particular type ofline switch shown in said British Patent No. 1419 of 1910. As shownherein, the usual plunger arm 5 and cut-ofi armature 6 are controlled bya double-wound magnet 7 Of the two-windings upon this magnet only thewinding 8 is strong enough to attract the plunger arm 5 from its normalposition, while the winding 9 can. only attract the cut-ofi armature 6from its normalposition, but can hold the plunger arm 5 in its operatedposition after it has once been pulled down by the winding 8. The usualline relay, instead of comprising a single winding upon the same core asthe pull-down and cut-0E windings 8 and 9, as is shown in said BritishPatent No. M19 of 1910, in the present instance comprises an entirelyindependent doublewound relay 10. This relay is preferably slightly slowacting. Connected in multiple with the line relay 10 of the line switchC, and therefore normally bridged across the line of the substation A,

there is the secondary winding-of an induction coil 11. Condensers 13and 1 1 are inserted in this bridge on either side of the inductioncoil. The primary winding ofthe induction coil is included in the localcircuit with the battery B and thetransmitter 15. This transmitter is ofsuitable character to operate in conjunction with the loud speakingreceiver 2 at the telephone, and may be simply a transmitter to bespoken into by an exchange attendant or other person, or may becontrolled by a phonograph or in any other manner to transmit any kindof message that may be desired to be transmitted to the substationthrough the medium. of the loud speaking receiver 2. The selector E isof the general type or. selector disclosed in United States LettersPatent No..815,321, granted March 13, 1906, to Keith, Erickson andErickson, bein modified, however, as shown in. said British Patent No.1419 of 1910 so as to operate in a two-wirefsystem, z. 6., a system inwhich the'central oflice apparatus is controlled from the callingsubstation over the two sides of the line in series. The selector F issimilar to the selector E, with the addition of the side switch". wiper85. As the specific structure of these but, like the selectors, ismodified in order to operate in atwo-wire system. Like the selectors,the connector is provided with a shaft (not shown) carrying the Wipers86, 87 and 88 and is controlled by the vertical magnet 89 and the rotarymagnet 90. The usual side switch is controlled by the private magnet 91in the usual manner. The connector is provided with a so-called back--bridge relay 177' through which the called substation is provided withtalking battery current, and with a ringer relay 164 through the mediumof which ringing current may be applied to the called line afterconnection is completed therewith.

The substation A and the line switch C are similar. to the substation Aand the line switch C, respectively. With the line switch C there is notshown a transmitting circuit similar to that'comprising the transmitter15 and induction coil 11 shown in connection with the line switch C,but, instead, there is shown a jack J which is normally bridged acrossthe line through the medium. of the condensers 17 and 18. With thisarrangement a transmitting circuit similar to that shown in connectionwith the line switch C (Fig. 1) may lee-provided with an ordinary plug,and may be connected with or, disconnected from the line at will throughthe medium of the jack J.

At M there is shown a ringing current generator and at L a busysignaling machine is shown comprising a current interrupter 93 and aninduction coil 94 F or operat ing the central oilice apparatus and forfurnishing talking current there is provided a battery B having onepole, preferably the positive, grounded at G.

Having given a general description of the apparatus 1 will explain in ageneral way the operations by which connection may be establishedbetween two automatic substations in the system shown. For example, itwill be explained how the substation A may obtain eonnectionwith thesubstation A, the number of which latter is assumed to be 2220. When thecalling subscriber re- 'moves his receiver preparatory to making.

a call, the switch hook rises, permitting the the spring 97 and intocontact with the spring 96, whereby th'e circuit of the ringer 29and'thecondenser 30 is broken and a bridge consisting of the substationtransmitter and receiver is closed across the line conductors '98 and99. j The closure of this bridge across the line completes an energizingcircuit through the line relay 10 of the switch C. lhis circuit extendsfrom ground G through theupper winding of the relay 10, springs 101 and102, line 99, springs 95 and 96, 32 and 31, receiver 25, transmitter 27line 98, springs 194; and 105 and the lower winding of the relay 10 tothe battery lead 100, thence through battery 13 to ground G. Theenergization of the relay 10 serves to close the circuit of theoperatlng winding 8 to cause the line switch to operate in the usual andwell-known manner to select an idle trunk-line leading to the firstselector E. The. winding 8, upon energizing, besides attracting theplunger arm 5 to causethe connection to be extended to the selector,also attracts the cut-ofl? armature 6, which not only disconnects theline relay 10 from the line, but also disconnects the sec-' twicemomentarily. Each time the springs 31 and 32 are separated, theenergizingcircuit of the line relay 77 of the selector E is broken,allowing said relay to be momentarily deenergized. This operation of theline relay77 causes the vertical magnet 16 to operate to raise theswitch wipers 67, 68

and 69 -to a position opposite the second level. .These wipers are thenrotated automatically to selectthe first idle trunk in this secondlevel, which trunk leads to one of the second selectors F. Connection isthus extended-to the second selector. The-calling subscriber nowoperates his calling device for the second digit 2. The secondselector Foperatesinresponse to the impulses for this digit in the same mannervasthe selector E and extends connection to an idle con nector H over thetrunk lines 134 and 135; The calling subscriber now'operates his dialfor the thirdadigit 2, momentarily separat same manner'asi described fortheffirs't digit.

Each time the impulse springs are separated for the third'digit, theenergizing circuit for the connector line relay 92 is broken momen};tarily. A This operation of the line relay op:

era'tes the connector in the well-known-manner to raise :it up-to thesecond level. The

connector isthen'in position to receive impulses for theilast digit 0.The operation of the substation calling device for this digit breaks theenergizingcircuit of the relay 92.; ten times; 'The rotary magnet 90then receives ten impulses and operates to rotatethe wipers ten steps,onto the contacts ofthe relay 149 is not open long enough to permit.

line No. 2220., The private magnet relay 149 is energized by thefirstimpulse to the ro-' tary magnet and again closes the circuit of theprivate magnet 91'. The circuit of the it to, deenergize until after thelast impulse has been delivered to the rotary magnet.

The relay 1 19'then deenergizes and breaks the circuit of the privatemagnet 91, which, if the called line is not already busy, in turndenergizes and permitstheside switch to pass to third position, wherebyconnec tion is completed between thecalling and called lines.

The side switch wiper 156, when in third position, extends the guardingpotential 7 from ground G through the private wiper 87 to the connectorprivate bank contacts of the called line, and also provides anenergi-zing circuit for the cut-off winding 157 of the line switch C.Thewinding 157, upon energizing, attracts the armature 158, whichoperates to disconnect the line relay 159 and the jack J from the calledline. When the side switch wiper 150 of the connector reaches thirdosition, the energizing cirouit is 'establis ed for the ringer relay164. This circuit extends from ground G through the interrupter 165,springs 171 and 170, relay'164 and the side switch wiper 150 to thebattery lead 100. Since this circuit includes the interrupter 165, therelay 161 is energized only intermittently, Each time the relay l64'isenergized itoperates to disconnect the calling line; from the calledline and tobridge the generator M across the called-line soas-to ringthe bell 175. When the called subscriber removes his receiver, orassoon' thereafter as the relay 164 deenergizes,if, it. happens tobeenergized at the time, the'called substation is provided with talking.battery'current from the central office. The circuit over 1 which thistalking current flows extends from ground G 1 through the: side switchwiper 156, lower ywinding of the --relay 177, ringer relay springs 188and-189, side switchwiper 187,

shaft-wiper "88, linef16l,'- springs 186 and wiper 179, ringerfrelaysprings 18121191180 flIld'tliQ'llPPQP wind-ingiof therelay 177 to *thebattery lead: 100. The'connector-backbridge relaybl77 is energized bythis talking called subscriber a fter he has answered.

vrafter the conversation is" completed the frelease of' the central'oflice apparatus is initiated by the hanging up ofthe'rec'eiver at.-the;callingsubstation. When the receiver 25 is'restored to the switchhook 26, the

springs 95 and -96 are separated, thereby breaking theenergizing-circuit through the lconnector'line relay 92'. Therelay 92,upon 1 deenergizing, breaks the-"holding circuits of the release relays139,128 and 82 of the switches F and, E, respectively, whereby they-arereleased in the well-known manner.-

The relay 82 of the selector E, upon deenergizing, also destroys thecircuit of the .185], impulse springs,1'82,,-receiver 1.84, trans mitter183, line160, shaft lwiper 86, side switch ing the impulse springs 31and 32 inlthey holding winding 9 of the line switch C, whereby theplunger arm. 5 is permitted to restore to normal position to disconnectthe line from the first selector E, and the cut-off armature (3 ispermitted to restore to normal position to again connect the line relay10 and the central oiiice transmitting circuit with the line of thesubstation A.

In the above description it will be seen that the transmitting circuitcomprising the induction coil 11 and the transmitter 15 (Fig. 1) and thejack J (Fig. 3), by means of which a similar transmitting circuit may beconnected with the subscribers line, is disconnected from thesubscribers line, either when the subscriber removes his receiver fromthe switch hook to initiate a call, or when a connector switch Hcompletes connection with the called line. Thus it will be seen thatwhen a subscriber wishes to call another subscriber in the ordinary way,no sounds are transmitted to the con nected subscribers from the specialtransmitting circuit at the central office. If. however, a subscriberwishes to receive the message that is being transmitted from the specialtransmitting circuit at the central oiiice, he simply operates the key Kto bridge the special receiver 2 across the line. Since this receiver isbridged across the line through the condensers, it does not form aconductive path for direct current, and therefore does not energize theline relay 10 to operate the line switch C; and since the induction coil11 is connected with the line as long as the line switch C is notoperated or its winding 9 energized, the subscriber may, through themedium of the special re ceiver2, hear the message which is beingtransmitted through the transmitter 15 and the induction coil 11. Itwill be seen that while any subscriber is receiving the in formationfrom this special transmitting circuit, his line is not prevented frombeing called by some other subscriber, and that in case his line iscalled this special transmitting circuit will be disconnected from theline by the energization of the cut-ofi 'winding'of the line. switch Cof the called line as soon as the connector switch com.- pletesconnection therewith.

In Fig. 6 there is shown a manual telephone substation comprising theusual receiver 201, transmitter 202, ringer 203 and condenser 204.At-the central ofiice there are allotted to the lines of this manualsubstation the usual answering jack J one or more multiple jacks J, line"lamp 205, line relay 206 and cut-ofi relay 207. At the substation thereis provided a receiver 210 similar to the receiver 2 (Fig. 1) which maybe manually connected withithe line through the medium of the key K. Atthe,central ofiice there is shown a special transmitting circuitcomprising an induction coil 211 and transmitter 212, which circuit isnormally connected with the line in multiple with the line relay in thesame manner as described in connection with the automatic substation. inF ig. 1. In this instance the subscriber may hear the sounds which arebeing transmitted by this special transmitting circuit by simplyoperating the key K to connect the receiver 210 with the line in thesame manner as explained in'connection with Fig. 1. YJhen the subscriberwishes to call some other subscriber, or is called, the induction coil211 is disconnected from the line by the energization of the cut-offrelay 207 whenever a plug of the operators cord circuit is inserted intoa acl: of the line.

It may often be more convenient to connect the special central oflicetransmitting circuit to the line at some other point than at the lineswitch in an automatic system, or at the regular cut-off relay in amanual system, as has been hereinbefore described. For instance, it maybe more desirable to connect this transmitting circuit to the line atthe distributing frame. This circuit may be connected to the line at anypoint desired by the use of a special relay, such as shown in Fig. at.In this figure the conductors 214: and 215 represent a portion of theline circuit between the substation and its terminus at the centraloflice. The conductors 216 and 217 are assumed to lead to thetransmitting circuit at the central office. These conductors areconnected to the line circuit through the normally closed contact of arelay 218. The relay 218 should be connected in multiple with the cut-0Hrelay of the linethat is, the conductor 219 should be connected with theconductor corresponding to the conductor 220 in Fig. 1, or the conductor221 in Fig. 6. The battery terminal of the relay should, of course, beconnected with the same terminal of the battery to which the cut-ofiirelay of the line switch with which it is associated is connected.

In all thecircuits hereinbefore described the central oiiicetransmitting circuit and the special receiver at the substation arebridged across the line. In 5 there is represented. diagrammaticallycircuit arrangements whereby this apparatus is operated over av circuit,one side of which includes thetwo sides of the telephone line inparallel, while the other side of the circuit is formed through theground or a common returnthat is, the transmitting circuitand receiverare included in ground taps which are taken off from a point between twocondensers which are bridged across the line.

It will thus be seen that l have provided a very convenient andefficient circuit arrangement whereby the subscribers of an automatic ora manual exchange can be supplied with music or with news or any otherdesired information. While it have illustrated in Fig. 1 merely atransmitter for supplying the desired information, it is obvious thatthe information or music could be supplied from a record and,furthermore, that the vibrations received from such 'record could beamplified to a sufficient degree so that a single record andmastertransmitter operated thereby could be employed for supplying a largenumber of subscribers.

Various other modifications will readily suggest themselves to thoseskilled in the art and come Within the scope of my invention.

\Vhat I claim as my invention is 1. In a telephone system, a subscribersline, a special service telephone set normally connected with said line,and means for extending connection from said line to a secondsubscribers line and for automatically disconnecting said specialservice set from the line, the said means comprising a magnet forperforming said automatic disconnection.

2. In a telephone system, a subscribers line, a telephone receiveradapted to be bridged across said line, a special service set normallybridged across said line at. the central station, and means forautomatically disconnecting said set from the line, the said meanscomprising a magnet for performing said automatic disconnection.

3. In a telephone system, a subscribers line, a substation set locatedthereon, a special service telephone receiver at said subtation, meansfor bridging said receiver across said line, a special servicetransmitter normally bridged across said line at the central station,and means for disconnecting said special service set from the line Whenoperation of said switch for disconnecting said ,set from the line.

5. In a telephone system, a subscribers.

line, a special service set normally bridged across said line, andautomatic means for disconnecting said set from the line when connectionis made With said line, the said means comprising a magnet forperforming said automatic disconnection.

6. In atelephone system, a subscribers" line, means for extendingconnection from said line, a telephone-receiver, means for bridging saidreceiver across the line Without operating said, first mentionedconnecting means, a special service set normally bridged across saidline at the central station, and means'for automatically discon-'necting said set from said line.

7. In a telephone system, a subscribers line, a substation set thereonincluding a receiver, means for bridging said receiver.

means for bridging said special receiver across said line in series witha condenser, a special service set normally bridged across said line atthe central station, and means for automatically disconnecting saidservice set from said line, the said means comprising a magnet forperforming said automatic disconnection.

8. In a telephone system, a subscribers line, a substation set thereonincluding a receiver, means for bridgingsaid receiver across said line,a special telephone receiver, means for bridging. said speciarreceiveracross said line in series with a condenser, a special service setnormally bridged across said line at the central station, means forextending connection from said line, and means for automaticallydisconnecting said special service set from the line When saidconnection is extended therefrom, the said means comprising a magnet forperforming said automatic disconnection.

9. In a telephone system, a subscribers line, a substation set thereonincluding a receiver, means for bridging said receiver across said line,a special telephone receiver, means for bridging said special receiveracross said line in series with a condenser, a special service setnormally bridged across said line at the central station, andmeans forautomatically disconnecting said service set from said line, the saidmeans comprising a magnet for performing said automatic disconnection. r

10. In atelephone system, a subscribers line, a substation set thereonlincluding a I receiver, means for brldging sald receiverspecial serviceset from the line Whensaid' connection is extended therefrom, the. saidmeans comprising a magnetifor performing said automatic disconnection.

'11. In a telephone system, a subsoribers line, a substationset' thereonincluding a telephone receiver, means for extending "connection fromsaid line, said'jmeans controlled by the switohhookto extend theconnection upon removal of the receiver, a second telephonereceiver,fmeans for bridging said sec- .ond recelver across saidkllneWithout operating said means, an'd 'a' special service set bridgedacrosssaid line atthe central station. 1

1.2. In a telephone system, a subscribers line, a. substation setthereonincluding a telephone receiver, means for extending connectionfrom said line, sa d meafis'controlled by the switch hook to extend theconnection upon removal of the receiver, a second telephone receiver,means for bridging said second receiver across said line without operating said means, a special service set bridged across said line at thecentral station, and means for automatically disconnecting said specialservice set from the line when connection is extended therefrom.

13. In a telephone system, a subscribers line, a telephone receiver,means for brit 5;- ing said receiver across said line, a special servicenormally bridged across said line at the central station, a cut-offrelay associated with said line, and means controlled by the operationof said cut-oil relay for disconnecting said set from the line ll. In atelephone system, a subscrilier s line, a substation set thereon, atrunk-selectswitch for extending connection from said line, means foroperating sail switch upon the removal of the receiver from the hook thesubstation, a loud speaking telephone receiver associated with said lineand means for bridgi said loud speaking re ceiver across said line withoperation of said trunk-st. a special service set bridget. at thecentral station.

15. In a telephone system, a suhscriher s line, a substation setthereon, a trunk-selecting switch for extending connection from saidline, means for operating said switch. upon the removal of the receiverfrom the 1g switch ind across said line phone receiver associated withsaid li a an means for bridging said loud spez. ceiver across said linewithout ca operation of said Lillllli'SElGChlllQi, swit special serviceset bridged across saio. at the central. station, and means for amaticall y disconnecting om the lir when line, a substation set thereon,a trunk-selecting switch for extending connection from said line, meansfor operating said switch upon the removal of the receiver from the hookat the substation, a loud speaking telephone receiver associated withsaid line and means for bridging said loud speaking receiver across saidline without causing the operation of said trunk-selecting switch, aspecial service set bridged across said line at the central station, acut-off relay associated with said trunk-selecting switch, and meanscontrolled by the operation of said cut-oft relay for disconnecting saidspecial service set from the line.

11'. In a telephone system, a subscribers line, a trunk-selecting switchfor extending connection from said line, a telephone receiver, means forbridging said receiver across said line to cause the operation of saidswitch, a second. receiver, means for bridging said second receiveracross said line in series with a condenser to thereby prevent operationof said switch, and a specialv service set bridged across said line atthe central stat-lon a telephone system, a suhscribefis line, atrunk-selecting switch for extending connection from said line, atelephone ceiver, .n' ans for bridging said receiver across line tocause the operation of said switch, a second receiver, means forhridping said second receiver across said line in series with acondenserto thereby :revent operation of said switch, a special 11065bridged across said line at the 'al station, and means for automatiby meat Chicago, Cook county, I I, this 8th day of May, 1912.

TALBOT G. MARTIN.

Ear

nonnsnzv.

